Cerebrovascular diseases are among the leading causes of mortality and morbidity. Patients who experience a cerebrovascular accident, more commonly known as a “stroke,” may experience either a gradual or an abrupt impairment of brain function, which is caused by a disruption of blood flow to (or within) the brain. Diseases that affect the arterial walls of blood vessels can lead to occlusions or partial occlusions (stenosis) that diminish blood supply. One of the most common arterial diseases is atherosclerosis, and when this condition is complicated by thrombosis or embolism, it is a frequent cause of stroke.
In some cases, stroke is associated with heart disease. Where stroke is caused by heart disease, it is typically due to embolism of thrombotic material that forms on the atrial or ventricular walls of the heart or on the valves on the heart's left side. This thrombotic material can detach and move as an embolus through the arterial circulation. Emboli can occlude arteries, including the larger arteries, in the brain. The most common causes of such “cardioembolic” stroke are nonrheumatic (non-valvular) atrial fibrillation (AE), prothestic valves, rheumatic heart disease (RHD), ischemic cardiomyopathy, congestive heart failure, myocardial infarction, and protruding aortic arch atheroma (AAA). Patients recovering from surgery are also more prone to cardioembolic stroke. The disorders described here are treated in different ways, including with drugs and surgery (e.g., carotid endarterectomy). Where the patient has an occlusive disease, they may undergo carotid angioplasty or receive a carotid stent.
While angioplasty, carotid stenting, and other procedures (such as endarterectomy) target the opening of occluded arteries, they do not prevent new plaques from forming. Moreover, these treatments only provide a solution to localized problems; they do not prevent proximal embolic sources. For example, an embolus formed at a remote site (e.g., within the heart or ascending aorta) may still pass through a reopened stenosis in the carotid artery and occlude smaller arteries in the brain. This is a significant problem because about one-third of patients suffering from carotid occlusion also have proximal embolic sources. Similarly, endarterectomy is not suitable for intracranial arteries or those in the vertebrobasilar system since these arteries are positioned within environments that do not lend themselves easily to surgical procedures (brain tissue and bone tissue) or are very small in diameter.
While stroke has been recognized as a leading cause of death, many stroke victims survive with substantial long-term disability. Their disabilities may be manifest as physical impairment due to motor weakness and lack of coordination, as a cognitive impairment including derangement in planning and executing complex tasks, or both. While some recovery is usually possible, victims of severe strokes often remain debilitated for the remainder of their lives.